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The cartographic data on anthropogenically transformed areas within the Ural River basin were analyzed to reveal the features of their spatial heterogeneity. The characteristics of the distribution and long-term development dynamics of the main types of nature management, settlement system, transport infrastructure facilities, and large industrial plants were taken into account. The main factor of the spatial distribution of various types of economic activity was found to be the difference in the natural-resource potential due to the latitude-zonal and geological-geomorphological diversity of landscapes in the drainage area. It has been found that the most deeply transformed areas are located along the Ural River valley, which is due to the existing settlement system and the presence of guaranteed reserves of water resources. An important factor of the transformation of the Ural River drainage area is the mining industry, which forms large industrial agglomerations and serves as the main source of pollutants that enter river water.

Long-term variations of ecological and hydrological parameters governing the natural reproduction of sturgeon are analyzed. It was found that long-term variations of hydrological characteristics are taking place against the background of cyclic development of phases with different water abundance and transformation of the annual redistribution of runoff. The contribution of long-term runoff regulation by the Iriklinskoe Reservoir to water regime variations in the Ural River is considered for its middle reaches. A conclusion is made regarding the need to restore the sturgeon herd in the Northern Caspian Sea. Recommendations are made regarding the priority measures for preserving the potential of sturgeon spawning grounds in the middle reaches of the Ural River.

Weather-climatic conditions are one of the leading factors forming fire dangerous satiations in the arid and semi-arid regions. Intra-continental position of the Ural-Caspian area promotes to reveal the diversity of climatic conditions and estimate the current trends in terms of the latitudinal-zonal change of landscapes and an increase of gradient of continentality. Results of analysis of the principal weather-climatic conditions – temperature, air precipitation, hydrothermal terms, wind regime, insolation) are summarized in the paper. Also, we identified spatio-temporal peculiarities of their long-time and current dynamics. The received results were analyzed in the aspect of the formation of fire dangerous situations in different landscapes of the examined region. Long-term archives on heat anomalies FIRMS served as principal data on grass fires. We have detected and confirmed that the most significant trends of the regional climate change are: a) growing air temperature occurring everywhere in frost-free seasons of a year; b) the cyclic dynamics of precipitation with the modern trend to aridization; c) annual distribution of rainfall; d) intensification of anomality of principal climatic parameters with the display of contrasting waves of heat and cold. All these tendencies directly (fire dangerous weather situations) or indirectly (productivity and a state of the vegetation cover) form the dynamics of grass fires. Nevertheless, the role of separate meteorological indicators and weather-climatic conditions, on the whole, are not often statistically significant in wildfires’ development. It is conditioned by the more substantial role of an anthropogenic factor that, in its turn, combines stochastic and purposeful agricultural sources of fires’ emergence.

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X23050252

The study data obtained on regional climate changes (surface layer temperature and atmospheric precipitation) in the Ural River basin are reported for a 70-year period (1950–2020). Variations in the basic parameters of the regional climate in the basin studied were obtained by standard statistical data analysis, as well as by calculation of the integral climate anomaly indices. Statistically significant linear trend coefficients illustrate a steady increase in the average annual air temperature in the Ural River basin. The largest contribution to the growth of this parameter is made in the first three months of the calendar year (January–March) and the autumn months (October–November). The long-term course of precipitation values is devoid of unidirectional and statistically significant trends. The important macroregional trend is an increase in precipitation during the cold period. In conclusion, it should be noted that the diverse physical and geographical conditions of the regional climate are indicative of a spatially nonuniform response to the global and macroregional changes.

The results of the regional climate change research on the example of the Volga-Ural steppe region are presented. Spatial and temporal patterns in the long-term (1960-2020) dynamics of atmospheric humidification are analyzed. It was revealed that the long phase with increased precipitation, which lasted in the region from about 1980 to 2010, was replaced everywhere by a clearly represented dry phase, especially in the Southern Urals and the Trans-Urals. There is also an intra-annual redistribution of precipitation for all weather stations (an increase in the share of the cold period precipitation and a decrease in the warm period rainfall), which leads to the levelling of humidification conditions. Speaking about the calendar months, the transformation of atmospheric humidification for separate periods of 1960-2020 at weather stations is quite multidirectional. The transformation of atmospheric humidification conditions occurs at the background of significant changes in the temperature regime: there is an increase in average annual indicators everywhere (on average by 1°C over 40 years) and average monthly temperatures in the first half of the year (from January to May). It is stated that against the air temperature background, changes in the humidification parameters can lead to the necessity of adapting various types of steppe environmental management to changing weather and climatic conditions.

The regional specifics of water use in the transboundary basin of the Ural R. are studied. The diverse problems of dependable water use in the region are caused by the interaction of natural and anthropogenic factors. Considering the space and time variations of river runoff, a possible approach to solving water use problem is runoff regulation. To effectively solve the problem of water use requires the search for an organizational and legal form of institutional interaction within the transboundary basin of the Ural R.

The natural conditions and the anthropogenic factors governing the formation of the environmental-hydrochemical situation in the rivers of the upper part of Ural R. basin are analyzed. Pollution transport is partially taking place under the conditions of hampered water exchange, caused by the structure of river channels and runoff regulation. The study confirms the uneven distribution of heavy metal concentrations in river water in different seasons, which is mostly due to differences in river runoff characteristics. The long duration and the high intensity of anthropogenic impact have considerably weakened the stability of river systems.